Inflated balls such as tennis balls and squash balls are hollow with an interior that is filled with gas under pressure to provide proper resiliency and bounce. However, over time such balls leak and lose their pressure as the gas leaks through the porous membrane of the ball, eventually rendering the ball unacceptable for use. It is known that by maintaining tennis balls in a pressurized can such balls can be kept pressurized indefinitely. Pumps have been developed for use with tennis ball containers but most have been difficult to operate and many have been too complex to be practical.
U.S. Pat. No. 3,888,347 issued to Kramer discloses a hand operated pump attached to the side wall of the container in which the outlet of the pump communicates through a hole in the sidewall of the container. A hand operated piston type pump requires a user to move the piston up and down in close proximity to the sidewall of the can, making it somewhat difficult and awkward to move. Moreover, a custom can is required to accommodate the pump.
U.S. Pat. No. 4,019,629 issued to Dubner et al. discloses a piston-type pump having a housing which fits over the outside end of the can. Not only is it difficult to hold the housing onto the can while lifting the piston, the low compressive strength of the can makes the can susceptible to damage and leakage.
U.S. Pat. No. 4,020,948 issued to Won discloses a replacement container rather than a pump adapted to be affixed to a standard container. Won shows two telescoping tubes with sliding seals between the two. Such a design would be expensive to fabricate and, considering the large area requiring sealing, there would be considerable likelihood of leakage.
U.S. Pat. No. 4,124,117 issued to Rudy discloses utilizing a chemical within the container and a suitable fluid that reacts with the chemical to generate a gas at atmospheric pressure to elevate the pressure within the ball. Each time the container is reused a new charge of chemical and liquid is necessary. The need to recharge the chemical is inconvenient as it must usually be done at the place where a supply of the chemical is available.
U.S. Pat. No. 5,311,988 issued to Bronson discloses a sleeve dimensioned to receive an open end of a standard container and which seals against a lip of the container. As the sleeve is pushed against the container it compresses the gas within and pressurizes the container. Development of pressure depends upon sealing all around the perimeter of the container open end. However, the end of the container is often flexible and relatively fragile. Thus, such a sleeve may not work on plastic containers or even metal ones having thin aluminum walls.
Accordingly, it is an object of the invention to provide an improved device for repressurizing a tennis ball container. It is a further object to provide a pump which can be easily attached and removed from an open end of a tennis ball container without damaging the end of the container. It is yet a further object of the invention to provide a repressurizing pump whose operation does not depend upon the number of balls in the container.